Re: [boost] task_array<n> and variadic templates

Subject: Re: [boost] task_array<n> and variadic templates
From: vicente.botet (vicente.botet_at_[hidden])
Date: 2008-11-19 11:36:11

----- Original Message ----- 
From: "Yechezkel Mett" <ymett.on.boost_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Wednesday, November 19, 2008 4:32 PM
Subject: Re: [boost] task_array<n> and variadic templates

> 
> On Wed, Nov 19, 2008 at 5:08 PM, Vicente Botet <vicente.botet_at_[hidden]> wrote:
>>
>> Comming back to my example, I need to store the tasks on an array. I do it now like this:
>>
>> template <>
>> struct task_array<3> {
>>    task arr_[3];
>>    template <typename F_1, typename F_2, typename F_3>
>>    task_array(F_1 f1, F_2 f2, F_3 f3) {
>>        arr_[0]=task(f1);
>>        arr_[1]=task(f2);
>>        arr_[2]=task(f3);
>>    }
>> };
>>
>>
>> I don't see a simple way to do it with variadic templates other than recursion.
>>
>> Is there a simple way to achieve this something like
>>
>> template <std::size N>
>> struct task_array {
>>   task arr_[N];
>>   template <typename... F>
>>    task_array(F... f) {
>>        static_assert(sizeof...(T) == N, "Constructor must provide N parameters")
>>    {
>>        arr_={task(f)...};
>>    }
>> };
> 
> Recursion is the way to do anything with variadic templates :-)
> But the following should work in theory:
> 
> template <std::size N>
> struct task_array {
>  task arr_[N];
>  template <typename... F>
>   task_array(F... f)
>     : arr_({task(f)...})
>   {
>       static_assert(sizeof...(T) == N, "Constructor must provide N parameters")
>   }
> };
> 
> if you can find a compiler that supports the new initialisation syntax, that is.

I was looking for confirmation.
Thanks,

Vicente